Field of the Invention
The present invention relates to a toner used in, for example, electrophotographic methods, electrostatic recording methods, and magnetic recording methods.
Description of the Related Art
Developing systems that use a magnetic single-component developer containing a magnetic toner have been aggressively used in black-and-white image-forming apparatuses (copiers and laser beam printers).
Magnetic single-component developers support a simpler developing system than those in case of two-component developers and nonmagnetic single-component developers and are thus advantageous with regard to size reduction and cost reduction.
In response to the growing awareness of promoting efficiency in the office, the demands on black-and-white image-forming apparatuses are growing more diverse and the level of these requirements is also increasing.
Specifically, responses are being required to demands for running cost reductions, less maintenance, smaller sizes, higher speeds, better energy savings, and support for media diversity.
For example, increasing the toner fill amount per toner cartridge unit can be contemplated in order to lower the running costs and reduce maintenance.
On the other hand, reducing the size of the image-forming apparatus requires a reduction in the toner fill volume in the toner cartridge and a reduction in the size of components such as the developing sleeve.
In order for size reduction and the toner fill amount—which are in conflict as indicated above—to co-exist, investigations are underway into high fill density cartridges, which have increased toner fill densities, but at present there are still many problems.
Reducing the amount of heat during fixing of the toner to paper is effective for responding to higher speeds for an image-forming apparatus as well as responding to greater energy savings, and there is demand for the development of toner that can be fixed to paper at ever lower temperatures (improved low-temperature fixability, i.e., a lower fixation temperature lower limit).
Viewed from the perspective of supporting various media, there is demand for a toner that resists hot offset even when large amounts of heat are applied to the toner during fixing by using high temperatures for fixing unit temperature control or lowering the print speed (improved hot offset resistance, i.e., a higher fixation temperature upper limit).
Based on these considerations, there is demand for a toner that has a wider temperature interval between the fixation temperature lower limit and the fixation temperature upper limit, i.e., that has a broader fixing margin.
It is known that a certain effect with regard to broadening the fixing margin is obtained by establishing a broader molecular weight distribution for the binder resin incorporated in a toner (Japanese Patent Application Laid-open No. 2014-80515).
With regard to magnetic toner that contains magnetic particles, Japanese Patent Application Laid-open No. 2002-278146 and Japanese Patent Application Laid-open No. H10-182163 propose that an improved toner performance, e.g., developing performance and so forth, be brought about by improving the magnetic particles.